1. Field of the Invention
The present invention relates to methods and apparatus for incorporating a second phase or miscible ingredient into the production of a non-Newtonian plastic product and in particular to the production of food products, including food products which are generally frozen at room temperature or food products that are generally spreadable at room temperature.
2. Prior Art
Referring to FIG. 1, a prior art system 100 is shown. System 100 is used in the production of a food product, such as margarine. In FIG. 1, a food product base source 102 provides a food product base to a scraped surface heat exchanger 104 or A-unit through a positive displacement pump 106. The food product base is mixed together with a gas provided by a gas source 108 at the scraped surface heat exchanger 104. Coolant 110, such as ammonia, is circulated through scraped surface heat exchanger 104 thereby chilling the mixture of the food product base and the gas.
From the scraped surface heat exchanger, if a softer product is desired the chilled mixture of the food product and the gas is provided to one of a whipper (not shown) and a B-unit 112. The B-unit provides crystallization time allowing fat crystals to form under gentle mixing. The amount of mixing varies the product produced. Too much mixing with the B-unit makes the product too soft and too little mixing results in the product being too brittle. From the B-unit 112, the chilled mixture of the food product base and the gas is provided to a filler apparatus 114 which forms the mixture for packaging and/or packages the mixture. As shown in FIG. 1, the gas is added prior to the food product exiting the scraped surface heat exchanger 104.
A recycle circuit 116 is provided to take the product exiting unit 112 back to the food product base source 102. The chilled mixture of the food product base and the gas is reheated by heating device 118 prior to be returned to food product base source 102. The recycle circuit 116 is used for occasions when there are interruptions to the requirements of filler 114 or to achieve a steady state wherein the gas is more uniformly dispersed in the chilled mixture of the food product base. For example, for a high production rate filling operation, there is at least a five minute recycle period at the beginning of a thirty minute run to obtain a more uniformly dispersed gas in the chilled mixture of the food product base and a five minute recycle time at the end of the thirty minute run. As such, only twenty minutes of productive filling time is available. This is due to the high volume of material in the equipment and the time required to flush the equipment clean. In addition the metering of the gas phase often is an iterative process requiring several adjustments each requiring at least a 5 minute flush out time. This can lead to very long start-up cycles.
By recycling the chilled mixture of the food product base and the gas, it is difficult to control the proportion of gas in the subsequent chilled mixture of the food product base and the gas. The addition of the additional gas also reduces the ability of the scraped surface heat exchanger to transfer heat.
Further, in certain cases another component is added prior to the location of gas source 108, such as fish oil to margarine. The fish oil may become degraded by reheating through recycle circuit 116 or it could be damaged in addition process prior to chiller.
A need exists for a better system and method for incorporating a second phase into a non-Newtonian fluid product base.